1. Technical Field
The present disclosure relates to a sensing system and, more particularly, to a system for sensing state and position of a robot which is traveling along a predetermined path.
2. Description of Related Art
Nowadays, robots are widely used to perform repetitious or dangerous tasks. In order to control the robot, the state and position of the robot should be known as accurately as possible at any given time.
Generally, the robot can calculate its present position by using an absolute or relative coordinate system. Using one or the other of the above coordinate system the robot can calculate the traveled distance and the angular displacement from a reference point.
As an example of the use of an absolute coordinate system, the robot uses a global positioning system (GPS) to obtain its present position and calculates the path of next movement according to the comparison between the coordinates of the present position and the coordinates of the subsequent position. However, when a robot using GPS is indoors or in areas exposed to strong electromagnetic interference, the signals from the GPS satellites may be compromised and hence the robot spatial movements may not be precise.
A robot using a relative coordinate system comprises a distance detection sensor for detecting a traveling distance and an angle sensor for detecting rotation angle of the robot. In general, an encoder, which can detect revolutions of a traveling wheel, is widely used as the distance detection sensor, and a gyro sensor, which can detect relative angle, is widely used as the angle sensor. However, gyros have an error rate of approximately 5˜10% (percent) of measured angle. The errors may vary depending on temperature and humidity. The errors can be accumulative such that a robot cannot follow a predetermined path.
What is needed, therefore, is a system which can overcome the above-mentioned problems.